Vibrational energy transfer in organic molecules

Abstract

Calculations are presented of rate constants for the relaxation and excitation of five different vibrational modes of C₂H₄ in three dimensional collisions with ³He and ⁴He. A form of the vibrational close-coupling, rotational infinite order sudden method has been used, especially modified for the collisions of organic molecules with atoms. The atom-molecule potential energy surface is obtained from self-consistent field data. Calculations of rate constants for the average vibration-translation energy transfer are in good agreement with those obtained in a laser double resonance experiment at a temperature of 462 K, but the agreement is not so good at lower temperatures.